Add an EDN parameter doc emitter

[WickedShell]

This is the result of poking around a bit because I'd find EDN more convenient then XML for parsing. Depends upon edn_format being installed from pip.

Also removes the ,'s from the FLIGHT_OPTIONS on plane as it breaks the other parsers as well (IE the wiki looks bad http://ardupilot.org/plane/docs/parameters.html#flight-options-flight-mode-options )

For those familiar with EDN the structure this uses is:

{:date #inst "2018-12-06T08:32:34.091777Z" ; utc time the parameters were parsed
 :git-hash "14fc764a17"
 :vehicle "ArduPlane" ; vehicle name this parameter set maps out to
 "FORMAT_VERSION" {:name "FORMAT_VERSION"
                   :description "This value is incremented when changes are made to the eeprom format"
                   :user "Advanced"
                   :display-name "Eeprom format version number"}
 ; rest of parameters
}

In the map for each parameter :bitmask will contain a vector of the descriptions per bit (with a null if the bit has no known meaning), :values is a map of the floating point value to it's description, :increment is a floating point number, :range is a map containing a low and high key to be used for creating the range.

After more suffering this runs under both python 2 and 3.

[WickedShell]

I scope crept this on myself slightly, param_parse.py now accepts a --format command line option that specifies what emitter(s) to use. I was getting rather annoyed at creating a bunch of junk in my ArduPilot folder that wasn't even in gitignore (added them to the ignore list as well), and really only want the one file anyways.